Lift arm structure for power loaders



June 7, 1966 G. R. MIDTBO 3,254,730

LIFT ARM STRUCTURE FOR POWER LOADERS Filed Sept. 24, 1964 I NVENTOR. G.R. MIDTBO ATTORNEY United States Patent 3 254,7 80 LIFT ARM STRUCTIiREFGR POWER LOADERS Guy R. Midtho, Moline, 112., assignor to Deere &Company, Molina, IlL, a corporation of Delaware Filed Sept. 24, 1964,Ser. No. 398,850 3 Claims. (Cl. 214140) This invention relates to apower loader and more particularly to a specific constructionof the liftarm structure of the power loader. Still more particularly the inventionrelates to a method of producing lift arm structure that increases thestrength of the structure.

In a power loader normally mounted on a tractor, the loader is composedof a pair of lift arms horizontally pivoted at their rear ends on thetractor and having means at their forward ends adapted for mounting apower loader bucket. The arms are normally composed of box channelstructure and joined by structure extending across and interjoining thepair of arms forward of the tractor. The transverse structurenormallyrigidifies the entire assembly, but in most instances does not in anyway affect the strength of the individual lift arms. The lift arms mayin one form be composed of a pair of U-shaped channels welded togetherto form a box channel. However, such a construction is normally weaksince the welds at the upper and lower sides of the arm tend to be weakpoints in the structure. In other instances the entire lift arm iscomposed of a single piece with a centrally located longitudinallyextending welding bead extending on only one side of the lift arm. Sucha construction has the advantage of being considerably stronger over theformer construction. However, its big disadvantage is that it isrelatively expensive to so shape the lift arm, particularly sinceconventional lift arms do in fact have some type of a knee or bend toavoid obstructions on the tractor or frame.

With the above in mind, it is the primary purpose of the presentinvention to provide a new and novel construction of a lift armstructure utilizing the relatively cheap pair of complementary U-shapedchannels welded together by upper and lower longitudinally extendingbeads extending the full length of the arms. In combination with thistype of construction it is proposed to provide forwardly of the tractora transverse tubular member extending through the bight portions of bothU- shaped channels of the respective lift arms so that the tubularmember is opened to opposite sides of the lift arm structure. The outersurface of the tubular member is welded to the bight portions so thatthe end portion of the tubular member between the bight portions servesas a structural member interconnecting the bight portions andreinforcing the upper and lower Welding beads. The portion between thelift arms serves the conventional purpose of rigidly connecting the liftarms and maintaining proper spacing between the lift arms.

It is a further object of the invention to provide a method of buildinga lift arm composed of welding complementary U-shaped channels into abox-like channel. Beam receiving openings are cut through the bightportions of the U-shaped channels and a transverse tubular beam ormember is extended through the bight portions and welded to the edges ofthe openings.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art as the nature of the invention isbetter understood from the following description and as shown in theaccompanying drawings.

FIG. 1 is a forward side perspective view of a tractor and loaderincorporating the features of the present invention. 4

FIG. 2 is a figure showing the first step in manufacture of the liftarm.

Patented June 7, 1966 FIG. 3 is a perspective view of the arm structureshown in FIG. 2 and showing the second step in manufacture.

FIG. 4 is a view similar to FIG. 3 but showing a further step in themanufacture of the lift arm.

FIG. 5 is a perspective view of the lift arm structure.

FIG. 6 is a sectional view taken substantially along the line 66 of FIG.5.

A power loader 10 is supported on and extends forwardly of a tractor 11having a pair of rear traction wheels, the left wheel being indicated bythe reference numeral 12, and a pair of front steerable wheels 13, 14.An operators station 15, indicated in its location by a steering wheeland tractor seat, is supported on the rear of the tractor body 16.

The loader 10 is composed in part of a pair of main frames 18, 19rigidly mounted on the tractor body 16 at their rear ends on rear axlestructure, not shown, and at their forward ends to the main frame of thetractor body 16. Such a mounting arrangement is conventional and neednot be described other than generally. The frames 18, 19 include a pairof upright posts 25, 21 having at their upper ends transverse horizontalpivots 22, 23. A lift arm structure, indicated in its entirety by thereference numeral 25 extends forwardly from the pivots 22, 23 beyondtheend of the tractor body 16 and carries at its forward ends a powerloader bucket 26. A pair of lift cylinders 27, 25 extends between therespective posts 20, 21 and the lift arm structure 25. A pair of buckettilt cylinders 29, 3t) extends between the lift ann structure 25 and therear of the bucket 26 and operates to angularly locate the bucket aboutthe forward end of the lift arm structure 25.

The lift arm structure 25 is composed of a pair of identical lift arms35 and designated L-35, R-35 on the leftand right-hand sides of thetractor body. Each of the lift arms 35 is composed of a pair of U-shapedchannels 36, 37 one being designated as the inner channel and the otherbeing designated as the outer channel and having vertical bight portionsor sides 38, 39. The channels 36, 37 face one another and have theirhorizontal leg portions joined by welding. Consequently the first stepin manufacturing the lift arm structure is to weld adjoining edges ofthe U-shaped channels 36, 37 by upper and lower longitudinally extendingwelding beads 40, 41, extending completely around the longitudinaladjoining edges of the channels 36, 37 and to form the channels into abox structure. Thelift arm, when welded, is substantially identical tothat shown in FIG. 3.

Following welding of the channels 36, 37, transversely alined openings45, 46 are cut in the vertical sides or flanges 38, 39 of a pair of liftarms, as designated by L-35 and R-35. At the same time pivot openings47, 48 may be cut in the lift arms 35 to'receive the respective pivots22, 23 and the pivot pins connecting the bucket 26 to the forward endsof the arms. A pair of longitudinally spaced and upper and lowertransverse tubular beam members 50, 51 extends between lift arms L-35and R35. The beam members 50, 51 have their outer end portions extendthrough the openings 45, 46. The tubular members 50, 51 have their outersurfaces closely adjacent the edges of the openings 45, 46 and arewelded to the edges, such welding being shown at 52, FIG. 6. The beams50, 51, therefore, have outer end portions extending through thebox-like channels of the side beams 35 and the portions between thevertical sides or flanges 38, 39 serve as reinforcement for the welds40, 41 that interconnect the U-shaped channels 36, 37. The portion ofthe transverse tubular members 50, 51 between the respective lift armsL-35, R-35 serves to rigidly interconnect the arms and to maintain theproper spacing between those arms.

It should be recognized that the present structure offers the advantageof utilizing portions of the transverse beams 50, 51 as reinforcingstructural members extending transversely through the channels 36, 37.This permits the relatively cheaper construction of providing a pair ofU-shaped channels and fabricating the channels together While retainingstrength in the lift arms.

While only one form of the invention has been shown, it should berecognized that other forms and variations will occur to those skilledin the art. Therefore, while the preferred form and method ofconstructing the lift arms has been shown in concise and detailed mannerfor the purpose of clearly and concisely illustrating the prin ciples ofthe invention, it should be understood there is no intention to limit ornarrow the invention beyond the broad concept set forth in the appendedclaims.

What is claimed is:

1. Lift arm structure for a power loader adapted for longitudinalsupport on a tractor comprising: leftand right-hand fore-and-aftextending lift arms disposed on opposite sides of the tractor and havingone of their ends adapted for horizontal pivotal connection to thetractor and extending longitudinally from the ends to portions disposedbeyond an end of the tractor, each of the arms being composed of anouter U-shaped channel facing inwardly and a complementary innerU-shaped channel facing outwardly and joined by upper and lower centralfore-and-aft extending welding beads forming the adjoined U-shapedchannels into a box-shaped channel; and rigid transverse tubular membersrigidly joining the portions of the leftand right-hand lift arms beyondthe end of the tractor, each member having opposite end portionsextending through the inner and outer channels of the leftand right-handlift arms between the upper and lower beads with the outer surface ofeach end portion being welded to the upright flanges of the respectiveinner and outer channels.

2. Lift arm structure for a power loader adapted for longitudinalsupport on a tractor comprising: leftand right-hand fore-and-aftextending lift arms disposed on opposite sides of the tractor and havingone of their ends adapted for horizontal pivotal connection to thetractor and extending longitudinally from the ends to portions disposedbeyond an end of the tractor, each of the arms being composed of anouter U-shaped channel facing inwardly and a complementary innerU-shaped channel facing outwardly and joined by upper and lower Weldingforming the adjoined U-shaped channels into a box-shaped channel; and arigid transverse tubular member rigidly joining the portions of theleftand right-hand lift arms beyond the end of the tractor, the memberhaving opposite end portions extending through the inner and outerchannels of the leftand right-hand lift arms between the upper and lowerwelding with the outer surface of each end portion being welded to theupright flanges of the respective inner and outer channels.

3. Lift arm structure for a power loader adapted for longitudinalsupport on a tractor comprising: leftand right-hand fore-and-aftextending lift arms disposed on opposite sides of the tractor and havingone of their ends adapted for horizontal pivotal connection to thetractor and extending longitudinally from the ends to portions disposedbeyond an end of the tractor, each of the arms being composed of afabricated box-shaped channel having transversely spaced upright sidesand formed by welding longitudinal structural elements; and a rigidtransverse tubular member rigidly joining the portions of the leftandright-hand lift arms beyond the end of the tractor, the member havingopposite end portions extending through the transversely spaced uprightsides of the leftand righthand lift arms with the outer surface of eachend portion being welded to both sides of the respective lift arm.

References Cited by the Examiner UNITED STATES PATENTS 1,917,666 7/1933Russell 214-145 2,770,372 11/1956 Martinson 212-144 2,993,608 7/1961Womble 214-14O FOREIGN PATENTS 175,157 2/ 1922 Great Britain.

HUGO O. SCHULZ, Primary Examiner.

1. LIFT ARM STRUCTURE FOR A POWER LOADED ADAPTED FOR LONGITUDINALSUPPORT ON A TRACTOR COMPRISING: LEFT- AND RIGHT-HAND FORE-AND-AFTEXTENDING LIFT ARMS DISPOSED ON OPPOSITE SIDES OF THE TRACTOR AND HAVINGONE OF THEIR ENDS ADAPTED FOR HORIZONTAL PIVOTAL CONNECTION TO THETRACTOR AND EXTENDING LONGITUDINALLY FROM THE ENDS TO PORTIONS DISPOSEDBEYOND AN END OF THE TRACTOR, EACH OF THE ARMS BEING COMPOSED OF ANOUTER U-SHAPED CHANNEL FACING INWARDLY AND A COMPLEMENTARY INNERU-SHAPED CHANNEL FACING OUTWARDLY AND JOINED BY UPPER AND LOWER CENTRALFORE-AND-AFT EXTENDING WELDING BEADS FORMING THE ADJOINED U-SHAPEDCHANNELS INTO A BOX-SHAPED CHANNEL; AND RIGID TRANSVERSE TUBULAR MEMBERSRIGIDLY JOINING THE PORTIONS OF THE LEFT- AND RIGHT-HAND LIFT ARMSBEYOND THE END OF THE TRACTOR, EACH MEMBER HAVING OPPOSITE END PORTIONSEXTENDING THROUGH THE INNER AND OUTER CHANNELS OF THE LEFT- ANDRIGHT-HAND LIFT ARMS BETWEEN THE UPPER AND LOWER BEADS WITH THE OUTERSURFACE OF EACH END PORTION BEING WELDED TO THE UPRIGHT FLANGES OF THERESPECTIVE INNER AND OUTER CHANNELS.